/*
 * jcphuff.c
 *
 * Copyright (C) 1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains Huffman entropy encoding routines for progressive JPEG.
 *
 * We do not support output suspension in this module, since the library
 * currently does not allow multiple-scan files to be written with output
 * suspension.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jchuff.h"      /* Declarations shared with jchuff.c */

#ifdef C_PROGRESSIVE_SUPPORTED

/* Expanded entropy encoder object for progressive Huffman encoding. */

typedef struct {
	struct jpeg_entropy_encoder pub; /* public fields */

	/* Mode flag: TRUE for optimization, FALSE for actual data output */
	boolean gather_statistics;

	/* Bit-level coding status.
	 * next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
	 */
	JOCTET * next_output_byte;  /* => next byte to write in buffer */
	size_t free_in_buffer;  /* # of byte spaces remaining in buffer */
	INT32 put_buffer;   /* current bit-accumulation buffer */
	int put_bits;       /* # of bits now in it */
	j_compress_ptr cinfo;   /* link to cinfo (needed for dump_buffer) */

	/* Coding status for DC components */
	int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */

	/* Coding status for AC components */
	int ac_tbl_no;      /* the table number of the single component */
	unsigned int EOBRUN;    /* run length of EOBs */
	unsigned int BE;    /* # of buffered correction bits before MCU */
	char * bit_buffer;      /* buffer for correction bits (1 per char) */
	/* packing correction bits tightly would save some space but cost time... */

	unsigned int restarts_to_go; /* MCUs left in this restart interval */
	int next_restart_num;   /* next restart number to write (0-7) */

	/* Pointers to derived tables (these workspaces have image lifespan).
	 * Since any one scan codes only DC or only AC, we only need one set
	 * of tables, not one for DC and one for AC.
	 */
	c_derived_tbl * derived_tbls[NUM_HUFF_TBLS];

	/* Statistics tables for optimization; again, one set is enough */
	long * count_ptrs[NUM_HUFF_TBLS];
} phuff_entropy_encoder;

typedef phuff_entropy_encoder * phuff_entropy_ptr;

/* MAX_CORR_BITS is the number of bits the AC refinement correction-bit
 * buffer can hold.  Larger sizes may slightly improve compression, but
 * 1000 is already well into the realm of overkill.
 * The minimum safe size is 64 bits.
 */

#define MAX_CORR_BITS  1000 /* Max # of correction bits I can buffer */

/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.
 * We assume that int right shift is unsigned if INT32 right shift is,
 * which should be safe.
 */

#ifdef RIGHT_SHIFT_IS_UNSIGNED
#define ISHIFT_TEMPS    int ishift_temp;
#define IRIGHT_SHIFT( x,shft )	\
	( ( ishift_temp = ( x ) ) < 0 ?	\
					  ( ishift_temp >> ( shft ) ) | ( ( ~0 ) << ( 16 - ( shft ) ) ) : \
					  ( ishift_temp >> ( shft ) ) )
#else
#define ISHIFT_TEMPS
#define IRIGHT_SHIFT( x,shft )    ( ( x ) >> ( shft ) )
#endif

/* Forward declarations */
METHODDEF boolean encode_mcu_DC_first JPP( ( j_compress_ptr cinfo,
											 JBLOCKROW *MCU_data ) );
METHODDEF boolean encode_mcu_AC_first JPP( ( j_compress_ptr cinfo,
											 JBLOCKROW *MCU_data ) );
METHODDEF boolean encode_mcu_DC_refine JPP( ( j_compress_ptr cinfo,
											  JBLOCKROW *MCU_data ) );
METHODDEF boolean encode_mcu_AC_refine JPP( ( j_compress_ptr cinfo,
											  JBLOCKROW *MCU_data ) );
METHODDEF void finish_pass_phuff JPP( (j_compress_ptr cinfo) );
METHODDEF void finish_pass_gather_phuff JPP( (j_compress_ptr cinfo) );


/*
 * Initialize for a Huffman-compressed scan using progressive JPEG.
 */

METHODDEF void
start_pass_phuff( j_compress_ptr cinfo, boolean gather_statistics ) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	boolean is_DC_band;
	int ci, tbl;
	jpeg_component_info * compptr;

	entropy->cinfo = cinfo;
	entropy->gather_statistics = gather_statistics;

	is_DC_band = ( cinfo->Ss == 0 );

	/* We assume jcmaster.c already validated the scan parameters. */

	/* Select execution routines */
	if ( cinfo->Ah == 0 ) {
		if ( is_DC_band ) {
			entropy->pub.encode_mcu = encode_mcu_DC_first;
		} else {
			entropy->pub.encode_mcu = encode_mcu_AC_first;
		}
	} else {
		if ( is_DC_band ) {
			entropy->pub.encode_mcu = encode_mcu_DC_refine;
		} else {
			entropy->pub.encode_mcu = encode_mcu_AC_refine;
			/* AC refinement needs a correction bit buffer */
			if ( entropy->bit_buffer == NULL ) {
				entropy->bit_buffer = ( char * )
									  ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
																	MAX_CORR_BITS * SIZEOF( char ) );
			}
		}
	}
	if ( gather_statistics ) {
		entropy->pub.finish_pass = finish_pass_gather_phuff;
	} else {
		entropy->pub.finish_pass = finish_pass_phuff;
	}

	/* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1
	 * for AC coefficients.
	 */
	for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
		compptr = cinfo->cur_comp_info[ci];
		/* Initialize DC predictions to 0 */
		entropy->last_dc_val[ci] = 0;
		/* Make sure requested tables are present */
		/* (In gather mode, tables need not be allocated yet) */
		if ( is_DC_band ) {
			if ( cinfo->Ah != 0 ) { /* DC refinement needs no table */
				continue;
			}
			tbl = compptr->dc_tbl_no;
			if ( tbl < 0 || tbl >= NUM_HUFF_TBLS ||
				 ( cinfo->dc_huff_tbl_ptrs[tbl] == NULL && !gather_statistics ) ) {
				ERREXIT1( cinfo,JERR_NO_HUFF_TABLE, tbl );
			}
		} else {
			entropy->ac_tbl_no = tbl = compptr->ac_tbl_no;
			if ( tbl < 0 || tbl >= NUM_HUFF_TBLS ||
				 ( cinfo->ac_huff_tbl_ptrs[tbl] == NULL && !gather_statistics ) ) {
				ERREXIT1( cinfo,JERR_NO_HUFF_TABLE, tbl );
			}
		}
		if ( gather_statistics ) {
			/* Allocate and zero the statistics tables */
			/* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
			if ( entropy->count_ptrs[tbl] == NULL ) {
				entropy->count_ptrs[tbl] = ( long * )
										   ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
																		 257 * SIZEOF( long ) );
			}
			MEMZERO( entropy->count_ptrs[tbl], 257 * SIZEOF( long ) );
		} else {
			/* Compute derived values for Huffman tables */
			/* We may do this more than once for a table, but it's not expensive */
			if ( is_DC_band ) {
				jpeg_make_c_derived_tbl( cinfo, cinfo->dc_huff_tbl_ptrs[tbl],
										 &entropy->derived_tbls[tbl] );
			} else {
				jpeg_make_c_derived_tbl( cinfo, cinfo->ac_huff_tbl_ptrs[tbl],
										 &entropy->derived_tbls[tbl] );
			}
		}
	}

	/* Initialize AC stuff */
	entropy->EOBRUN = 0;
	entropy->BE = 0;

	/* Initialize bit buffer to empty */
	entropy->put_buffer = 0;
	entropy->put_bits = 0;

	/* Initialize restart stuff */
	entropy->restarts_to_go = cinfo->restart_interval;
	entropy->next_restart_num = 0;
}


/* Outputting bytes to the file.
 * NB: these must be called only when actually outputting,
 * that is, entropy->gather_statistics == FALSE.
 */

/* Emit a byte */
#define emit_byte( entropy,val )  \
	{ *( entropy )->next_output_byte++ = (JOCTET) ( val );	\
	  if ( --( entropy )->free_in_buffer == 0 ) { \
		  dump_buffer( entropy );} }


LOCAL void
dump_buffer( phuff_entropy_ptr entropy ) {
/* Empty the output buffer; we do not support suspension in this module. */
	struct jpeg_destination_mgr * dest = entropy->cinfo->dest;

	if ( !( *dest->empty_output_buffer )( entropy->cinfo ) ) {
		ERREXIT( entropy->cinfo, JERR_CANT_SUSPEND );
	}
	/* After a successful buffer dump, must reset buffer pointers */
	entropy->next_output_byte = dest->next_output_byte;
	entropy->free_in_buffer = dest->free_in_buffer;
}


/* Outputting bits to the file */

/* Only the right 24 bits of put_buffer are used; the valid bits are
 * left-justified in this part.  At most 16 bits can be passed to emit_bits
 * in one call, and we never retain more than 7 bits in put_buffer
 * between calls, so 24 bits are sufficient.
 */

INLINE
LOCAL void
emit_bits( phuff_entropy_ptr entropy, unsigned int code, int size ) {
/* Emit some bits, unless we are in gather mode */
/* This routine is heavily used, so it's worth coding tightly. */
	register INT32 put_buffer = (INT32) code;
	register int put_bits = entropy->put_bits;

	/* if size is 0, caller used an invalid Huffman table entry */
	if ( size == 0 ) {
		ERREXIT( entropy->cinfo, JERR_HUFF_MISSING_CODE );
	}

	if ( entropy->gather_statistics ) {
		return;     /* do nothing if we're only getting stats */

	}
	put_buffer &= ( ( (INT32) 1 ) << size ) - 1; /* mask off any extra bits in code */

	put_bits += size;   /* new number of bits in buffer */

	put_buffer <<= 24 - put_bits; /* align incoming bits */

	put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */

	while ( put_bits >= 8 ) {
		int c = (int) ( ( put_buffer >> 16 ) & 0xFF );

		emit_byte( entropy, c );
		if ( c == 0xFF ) {  /* need to stuff a zero byte? */
			emit_byte( entropy, 0 );
		}
		put_buffer <<= 8;
		put_bits -= 8;
	}

	entropy->put_buffer = put_buffer; /* update variables */
	entropy->put_bits = put_bits;
}


LOCAL void
flush_bits( phuff_entropy_ptr entropy ) {
	emit_bits( entropy, 0x7F, 7 ); /* fill any partial byte with ones */
	entropy->put_buffer = 0;   /* and reset bit-buffer to empty */
	entropy->put_bits = 0;
}


/*
 * Emit (or just count) a Huffman symbol.
 */

INLINE
LOCAL void
emit_symbol( phuff_entropy_ptr entropy, int tbl_no, int symbol ) {
	if ( entropy->gather_statistics ) {
		entropy->count_ptrs[tbl_no][symbol]++;
	} else {
		c_derived_tbl * tbl = entropy->derived_tbls[tbl_no];
		emit_bits( entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol] );
	}
}


/*
 * Emit bits from a correction bit buffer.
 */

LOCAL void
emit_buffered_bits( phuff_entropy_ptr entropy, char * bufstart,
					unsigned int nbits ) {
	if ( entropy->gather_statistics ) {
		return;     /* no real work */

	}
	while ( nbits > 0 ) {
		emit_bits( entropy, ( unsigned int )( *bufstart ), 1 );
		bufstart++;
		nbits--;
	}
}


/*
 * Emit any pending EOBRUN symbol.
 */

LOCAL void
emit_eobrun( phuff_entropy_ptr entropy ) {
	register int temp, nbits;

	if ( entropy->EOBRUN > 0 ) { /* if there is any pending EOBRUN */
		temp = entropy->EOBRUN;
		nbits = 0;
		while ( ( temp >>= 1 ) )
			nbits++;

		emit_symbol( entropy, entropy->ac_tbl_no, nbits << 4 );
		if ( nbits ) {
			emit_bits( entropy, entropy->EOBRUN, nbits );
		}

		entropy->EOBRUN = 0;

		/* Emit any buffered correction bits */
		emit_buffered_bits( entropy, entropy->bit_buffer, entropy->BE );
		entropy->BE = 0;
	}
}


/*
 * Emit a restart marker & resynchronize predictions.
 */

LOCAL void
emit_restart( phuff_entropy_ptr entropy, int restart_num ) {
	int ci;

	emit_eobrun( entropy );

	if ( !entropy->gather_statistics ) {
		flush_bits( entropy );
		emit_byte( entropy, 0xFF );
		emit_byte( entropy, JPEG_RST0 + restart_num );
	}

	if ( entropy->cinfo->Ss == 0 ) {
		/* Re-initialize DC predictions to 0 */
		for ( ci = 0; ci < entropy->cinfo->comps_in_scan; ci++ )
			entropy->last_dc_val[ci] = 0;
	} else {
		/* Re-initialize all AC-related fields to 0 */
		entropy->EOBRUN = 0;
		entropy->BE = 0;
	}
}


/*
 * MCU encoding for DC initial scan (either spectral selection,
 * or first pass of successive approximation).
 */

METHODDEF boolean
encode_mcu_DC_first( j_compress_ptr cinfo, JBLOCKROW *MCU_data ) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int temp, temp2;
	register int nbits;
	int blkn, ci;
	int Al = cinfo->Al;
	JBLOCKROW block;
	jpeg_component_info * compptr;
	ISHIFT_TEMPS

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if ( cinfo->restart_interval ) {
		if ( entropy->restarts_to_go == 0 ) {
			emit_restart( entropy, entropy->next_restart_num );
		}
	}

	/* Encode the MCU data blocks */
	for ( blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++ ) {
		block = MCU_data[blkn];
		ci = cinfo->MCU_membership[blkn];
		compptr = cinfo->cur_comp_info[ci];

		/* Compute the DC value after the required point transform by Al.
		 * This is simply an arithmetic right shift.
		 */
		temp2 = IRIGHT_SHIFT( (int) ( ( *block )[0] ), Al );

		/* DC differences are figured on the point-transformed values. */
		temp = temp2 - entropy->last_dc_val[ci];
		entropy->last_dc_val[ci] = temp2;

		/* Encode the DC coefficient difference per section G.1.2.1 */
		temp2 = temp;
		if ( temp < 0 ) {
			temp = -temp; /* temp is abs value of input */
			/* For a negative input, want temp2 = bitwise complement of abs(input) */
			/* This code assumes we are on a two's complement machine */
			temp2--;
		}

		/* Find the number of bits needed for the magnitude of the coefficient */
		nbits = 0;
		while ( temp ) {
			nbits++;
			temp >>= 1;
		}

		/* Count/emit the Huffman-coded symbol for the number of bits */
		emit_symbol( entropy, compptr->dc_tbl_no, nbits );

		/* Emit that number of bits of the value, if positive, */
		/* or the complement of its magnitude, if negative. */
		if ( nbits ) {  /* emit_bits rejects calls with size 0 */
			emit_bits( entropy, (unsigned int) temp2, nbits );
		}
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if ( cinfo->restart_interval ) {
		if ( entropy->restarts_to_go == 0 ) {
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	return TRUE;
}


/*
 * MCU encoding for AC initial scan (either spectral selection,
 * or first pass of successive approximation).
 */

METHODDEF boolean
encode_mcu_AC_first( j_compress_ptr cinfo, JBLOCKROW *MCU_data ) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int temp, temp2;
	register int nbits;
	register int r, k;
	int Se = cinfo->Se;
	int Al = cinfo->Al;
	JBLOCKROW block;

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if ( cinfo->restart_interval ) {
		if ( entropy->restarts_to_go == 0 ) {
			emit_restart( entropy, entropy->next_restart_num );
		}
	}

	/* Encode the MCU data block */
	block = MCU_data[0];

	/* Encode the AC coefficients per section G.1.2.2, fig. G.3 */

	r = 0;          /* r = run length of zeros */

	for ( k = cinfo->Ss; k <= Se; k++ ) {
		if ( ( temp = ( *block )[jpeg_natural_order[k]] ) == 0 ) {
			r++;
			continue;
		}
		/* We must apply the point transform by Al.  For AC coefficients this
		 * is an integer division with rounding towards 0.  To do this portably
		 * in C, we shift after obtaining the absolute value; so the code is
		 * interwoven with finding the abs value (temp) and output bits (temp2).
		 */
		if ( temp < 0 ) {
			temp = -temp; /* temp is abs value of input */
			temp >>= Al; /* apply the point transform */
			/* For a negative coef, want temp2 = bitwise complement of abs(coef) */
			temp2 = ~temp;
		} else {
			temp >>= Al; /* apply the point transform */
			temp2 = temp;
		}
		/* Watch out for case that nonzero coef is zero after point transform */
		if ( temp == 0 ) {
			r++;
			continue;
		}

		/* Emit any pending EOBRUN */
		if ( entropy->EOBRUN > 0 ) {
			emit_eobrun( entropy );
		}
		/* if run length > 15, must emit special run-length-16 codes (0xF0) */
		while ( r > 15 ) {
			emit_symbol( entropy, entropy->ac_tbl_no, 0xF0 );
			r -= 16;
		}

		/* Find the number of bits needed for the magnitude of the coefficient */
		nbits = 1;      /* there must be at least one 1 bit */
		while ( ( temp >>= 1 ) )
			nbits++;

		/* Count/emit Huffman symbol for run length / number of bits */
		emit_symbol( entropy, entropy->ac_tbl_no, ( r << 4 ) + nbits );

		/* Emit that number of bits of the value, if positive, */
		/* or the complement of its magnitude, if negative. */
		emit_bits( entropy, (unsigned int) temp2, nbits );

		r = 0;      /* reset zero run length */
	}

	if ( r > 0 ) {      /* If there are trailing zeroes, */
		entropy->EOBRUN++;  /* count an EOB */
		if ( entropy->EOBRUN == 0x7FFF ) {
			emit_eobrun( entropy ); /* force it out to avoid overflow */
		}
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if ( cinfo->restart_interval ) {
		if ( entropy->restarts_to_go == 0 ) {
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	return TRUE;
}


/*
 * MCU encoding for DC successive approximation refinement scan.
 * Note: we assume such scans can be multi-component, although the spec
 * is not very clear on the point.
 */

METHODDEF boolean
encode_mcu_DC_refine( j_compress_ptr cinfo, JBLOCKROW *MCU_data ) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int temp;
	int blkn;
	int Al = cinfo->Al;
	JBLOCKROW block;

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if ( cinfo->restart_interval ) {
		if ( entropy->restarts_to_go == 0 ) {
			emit_restart( entropy, entropy->next_restart_num );
		}
	}

	/* Encode the MCU data blocks */
	for ( blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++ ) {
		block = MCU_data[blkn];

		/* We simply emit the Al'th bit of the DC coefficient value. */
		temp = ( *block )[0];
		emit_bits( entropy, ( unsigned int )( temp >> Al ), 1 );
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if ( cinfo->restart_interval ) {
		if ( entropy->restarts_to_go == 0 ) {
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	return TRUE;
}


/*
 * MCU encoding for AC successive approximation refinement scan.
 */

METHODDEF boolean
encode_mcu_AC_refine( j_compress_ptr cinfo, JBLOCKROW *MCU_data ) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int temp;
	register int r, k;
	int EOB;
	char *BR_buffer;
	unsigned int BR;
	int Se = cinfo->Se;
	int Al = cinfo->Al;
	JBLOCKROW block;
	int absvalues[DCTSIZE2];

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if ( cinfo->restart_interval ) {
		if ( entropy->restarts_to_go == 0 ) {
			emit_restart( entropy, entropy->next_restart_num );
		}
	}

	/* Encode the MCU data block */
	block = MCU_data[0];

	/* It is convenient to make a pre-pass to determine the transformed
	 * coefficients' absolute values and the EOB position.
	 */
	EOB = 0;
	for ( k = cinfo->Ss; k <= Se; k++ ) {
		temp = ( *block )[jpeg_natural_order[k]];
		/* We must apply the point transform by Al.  For AC coefficients this
		 * is an integer division with rounding towards 0.  To do this portably
		 * in C, we shift after obtaining the absolute value.
		 */
		if ( temp < 0 ) {
			temp = -temp; /* temp is abs value of input */
		}
		temp >>= Al;    /* apply the point transform */
		absvalues[k] = temp; /* save abs value for main pass */
		if ( temp == 1 ) {
			EOB = k;    /* EOB = index of last newly-nonzero coef */
		}
	}

	/* Encode the AC coefficients per section G.1.2.3, fig. G.7 */

	r = 0;          /* r = run length of zeros */
	BR = 0;         /* BR = count of buffered bits added now */
	BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */

	for ( k = cinfo->Ss; k <= Se; k++ ) {
		if ( ( temp = absvalues[k] ) == 0 ) {
			r++;
			continue;
		}

		/* Emit any required ZRLs, but not if they can be folded into EOB */
		while ( r > 15 && k <= EOB ) {
			/* emit any pending EOBRUN and the BE correction bits */
			emit_eobrun( entropy );
			/* Emit ZRL */
			emit_symbol( entropy, entropy->ac_tbl_no, 0xF0 );
			r -= 16;
			/* Emit buffered correction bits that must be associated with ZRL */
			emit_buffered_bits( entropy, BR_buffer, BR );
			BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
			BR = 0;
		}

		/* If the coef was previously nonzero, it only needs a correction bit.
		 * NOTE: a straight translation of the spec's figure G.7 would suggest
		 * that we also need to test r > 15.  But if r > 15, we can only get here
		 * if k > EOB, which implies that this coefficient is not 1.
		 */
		if ( temp > 1 ) {
			/* The correction bit is the next bit of the absolute value. */
			BR_buffer[BR++] = (char) ( temp & 1 );
			continue;
		}

		/* Emit any pending EOBRUN and the BE correction bits */
		emit_eobrun( entropy );

		/* Count/emit Huffman symbol for run length / number of bits */
		emit_symbol( entropy, entropy->ac_tbl_no, ( r << 4 ) + 1 );

		/* Emit output bit for newly-nonzero coef */
		temp = ( ( *block )[jpeg_natural_order[k]] < 0 ) ? 0 : 1;
		emit_bits( entropy, (unsigned int) temp, 1 );

		/* Emit buffered correction bits that must be associated with this code */
		emit_buffered_bits( entropy, BR_buffer, BR );
		BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
		BR = 0;
		r = 0;      /* reset zero run length */
	}

	if ( r > 0 || BR > 0 ) { /* If there are trailing zeroes, */
		entropy->EOBRUN++;  /* count an EOB */
		entropy->BE += BR;  /* concat my correction bits to older ones */
		/* We force out the EOB if we risk either:
		 * 1. overflow of the EOB counter;
		 * 2. overflow of the correction bit buffer during the next MCU.
		 */
		if ( entropy->EOBRUN == 0x7FFF || entropy->BE > ( MAX_CORR_BITS - DCTSIZE2 + 1 ) ) {
			emit_eobrun( entropy );
		}
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if ( cinfo->restart_interval ) {
		if ( entropy->restarts_to_go == 0 ) {
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	return TRUE;
}


/*
 * Finish up at the end of a Huffman-compressed progressive scan.
 */

METHODDEF void
finish_pass_phuff( j_compress_ptr cinfo ) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Flush out any buffered data */
	emit_eobrun( entropy );
	flush_bits( entropy );

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;
}


/*
 * Finish up a statistics-gathering pass and create the new Huffman tables.
 */

METHODDEF void
finish_pass_gather_phuff( j_compress_ptr cinfo ) {
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	boolean is_DC_band;
	int ci, tbl;
	jpeg_component_info * compptr;
	JHUFF_TBL **htblptr;
	boolean did[NUM_HUFF_TBLS];

	/* Flush out buffered data (all we care about is counting the EOB symbol) */
	emit_eobrun( entropy );

	is_DC_band = ( cinfo->Ss == 0 );

	/* It's important not to apply jpeg_gen_optimal_table more than once
	 * per table, because it clobbers the input frequency counts!
	 */
	MEMZERO( did, SIZEOF( did ) );

	for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
		compptr = cinfo->cur_comp_info[ci];
		if ( is_DC_band ) {
			if ( cinfo->Ah != 0 ) { /* DC refinement needs no table */
				continue;
			}
			tbl = compptr->dc_tbl_no;
		} else {
			tbl = compptr->ac_tbl_no;
		}
		if ( !did[tbl] ) {
			if ( is_DC_band ) {
				htblptr = &cinfo->dc_huff_tbl_ptrs[tbl];
			} else {
				htblptr = &cinfo->ac_huff_tbl_ptrs[tbl];
			}
			if ( *htblptr == NULL ) {
				*htblptr = jpeg_alloc_huff_table( (j_common_ptr) cinfo );
			}
			jpeg_gen_optimal_table( cinfo, *htblptr, entropy->count_ptrs[tbl] );
			did[tbl] = TRUE;
		}
	}
}


/*
 * Module initialization routine for progressive Huffman entropy encoding.
 */

GLOBAL void
jinit_phuff_encoder( j_compress_ptr cinfo ) {
	phuff_entropy_ptr entropy;
	int i;

	entropy = (phuff_entropy_ptr)
				( *cinfo->mem->alloc_small ) ( (j_common_ptr) cinfo, JPOOL_IMAGE,
											   SIZEOF( phuff_entropy_encoder ) );
	cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
	entropy->pub.start_pass = start_pass_phuff;

	/* Mark tables unallocated */
	for ( i = 0; i < NUM_HUFF_TBLS; i++ ) {
		entropy->derived_tbls[i] = NULL;
		entropy->count_ptrs[i] = NULL;
	}
	entropy->bit_buffer = NULL; /* needed only in AC refinement scan */
}

#endif /* C_PROGRESSIVE_SUPPORTED */
